Hello all.
I would like to define a data type that is the super-set of several
types and then each of the proper subset types. For example:
data Foo = One | Two | Three | Four
data Odd = One | Three
data Even = Two | Four
This, of course, does not work. It seems that such a thing should
possible to express entirely in the type system, but I cannot think of
how. Would someone be so kind as to explain how this sort of thing can
be accomplished?
Thanks,
Brian